From single link MIMO to multi-user MIMO

For any given single link strategy for transmission over a MIMO channel with channel knowledge at both transmitter and receiver, we propose a general approach to reduce the interference when the strategy is used in an interference limited system. This solution has several interesting interpretations. The structure of the solution is shown to include the global optimum, even though it may be difficult to determine all parameters. However, a suboptimal choice is presented that can be implemented in practical systems using only local information. A numerical example illustrates the performance when trying to minimize the summed mutual information.